A stereoscopic image display apparatus capable of autostereoscopy is as an apparatus for displaying a stereoscopic image, for example, without a special device such as a polarized glass or a glass with shutter.
For example, in Japanese Patent No. 3323575 (pp 3, FIG. 1) . . . (reference 1), a plurality of images, each having a different view position, are respectively projected by a plurality of projectors from the back of a transmission type screen. By observing the transmission light through a lenticular lens located in front of the screen, a user can observe a stereoscopic image.
Furthermore, in Japanese Patent Disclosure (Kokai) PH9-0189884 (pp 4, FIG. 1) . . . (reference 2), on a projection type screen in which a plurality of rotatable reflection mirrors are arraged along a horizontal direction, a plurality of images each having different view position are projected by switching in time. In this case, the user can also observe a stereoscopic image.
Furthermore, in “H. Kaneko, T. Ohshima, O. Ebina and A. Arimoto, “Desktop Autostereoscopic Display Using Compact LED Projectors and CDR Screen”, SID 02 DIGEST, pp. 1418-1421, 2002”. . . (reference 3), a plurality of projectors projects an image onto a projection type screen having shape of corner reflection mirror. By observing the reflection light at a position of the projector, the user can also observe the stereoscopic image.
In order to widely use the stereoscopic display apparatus, the observable area of a stereoscopic image should be wide, and a scale of apparatus necessary to display the stereoscopic image should not be large. Especially, a small number of projectors necessary to display the stereoscopic image is important to prevent the scale of apparatus from being large. Without special function, it is desired that the stereoscopic image is displayed by one projector.
However, in the stereoscopic image display apparatus of the references 1 and 3, a plurality of projectors is necessary. Especially, in order to simultaneously observe a stereoscopic image from a plurality of view positions by extending an observable area, the number of projectors has to be increased. In this case, a scale of the apparatus becomes large.
Furthermore, in the stereoscopic image display apparatus of the reference 2, in synchronization with a projection image timely switched by a projector, rotation of reflection mirrors set on a screen has to be controlled. Accordingly, in the projector outgoing the image, a controller to synchronize rotation of the projection image with the reflection mirrors is necessary. In case of using this method, a usual projector cannot display the stereoscopic image.